PURPOSE: To promote drying and burning of sludge and soil by an effective inversion and stirring thereof in the dust incinerator in which a plurality of stokers are rotated to drop down the sludge and soil to be burned successively to the stokers at lower stages and the sludge and soil are dried while being inverted and stirred and finally burned.

CONSTITUTION: The stokers 1 journalled rotatably from horizontal position to vertical position around two central rotary shafts 2 of frames 6 in a furnace passage 9 surrounded by a furnace wall 8 are equipped with a number of fire grate 5 arranged symmetrically with respet to the central rotary shafts 2. The central rotary shafts 2 and fire grates 5 are provided with a number of projections 4 which protrude upward at the horizontal position. When the sludge and soil on the stokers 1 drop down by their own gravity when the stokers 1 incline, they hang on the projections 4, without dropping down directly in a mass. Thus the sludge and soil are stirred sufficiently and heated evenly with no part remained unheated. Accordingly, the drying time and burning time of the sludge and soil can be much shortened.